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Ch.1 - Introduction: Matter, Energy, and Measurement

Chapter 1, Problem 4d

Consider the two spheres shown here, one made of silver and the other of aluminum. (d) If you release the spheres simultaneously, they will have the same velocity when they hit the ground. Will they have the same kinetic energy? If not, which sphere will have more kinetic energy?

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Hi everyone for this problem. It says imagine you have two blocks of metals. One is composed of iron and the other is composed of platinum. When both blocks are released from a height at the same, they will have the same velocity as they hit the ground. Well, they also have equal kinetic energies. Okay, so we need to recall what is our kinetic energy equation That is. Kinetic energy Is equal to 1/2 of times mass times v squared. Ok, so here we're told that we have two metals. The first one is iron And the 2nd 1 is platinum. Okay. And we need to see if they're going to have equal kinetic energies. So that means let's first look at our relationship between mass and kinetic energy. They're directly proportional. So our kinetic energy is directly proportional to the mass. So that means we need to figure out what is our mass for each of these metals? When we look up our mass of iron, It is 55.86 grams per mole. And our mass of platinum Is equal to 195 . grams per mole. We're told that the velocity is the same. Okay, so that means the velocity of iron is equal to the velocity of platinum. So that means we can um it's constant. Okay, so in terms of weight, we can see that our platinum weighs more than iron. And because of that, they're not going to have the same kinetic energy because platinum is heavier than iron, it will have a greater kinetic energy. Okay, so this one's gonna have a higher kinetic energy then. Okay, sorry, It's the platinum. So our platinum is going to have a higher kinetic energy than our iron because it's heavier. So the answer is no, because platinum ways more than iron. Okay, that is the final answer to this problem, and I hope this was helpful.